Pneumatic jack



June 23, 1936. w .FEHR'MANN 2,045,524

PNEUMATIC JACK Filed An e, 19:55 2 Sheets-Sheet 1 ATTORNEY WITNESS WJune 23, 1936. w. A FEHRMANN 2 Sheets-Sheet 2 PNEUMATIC JACK Filed Aug.6, 1935 INVENTOR ATTORNEY I 1- 1 ES ELL ID'Q I I I I Q h ZzZZe 'A.ifirmmzr'z wrrusss;

Patented a... 23, 1936' UNITED Y STATES PATENT OFFICE mourn-1c ucnWalter A. Fehrmann, Vedado, Ilabana, cubs Application August 6, 1935.Serial No. 34,971

' 4 Claims. (01. 254-40) This invention relates to pneumatic :Iacks formotor vehicles and has for an object to provide broadly pneumatic jacksfixed to the axles and controlled by a distributing valve within reachof 5 the driver, the jacks preferably utilizing the power produced bythe explosions in the vehicle motor cylinders, although a compressed airpump and reservoir may be-used so that running ofthe motor may bedispensed with. I

10 More specifically. an object of the invention s to provide a novelpneumatic jack having a piston and a cylinder, the piston being soconstructed as to be reenforced against shocks, jars and lateralstresses when in operative position.

to manufacture, and which will not easily get out of order.

With the above and-other objects in view the invention consists ofcertain novel details of con-j 5 struction and combinations of partshereinafter fully described and claimed, it being understood thatvarious modifications may be resorted to within the scope of theappended claims without departing from the spirit or sacrificing any of.30 the advantages of the invention.

In the accompanying'drawings forming part! this specification,

Figure 1 is a top plan view of a motor vehicle I chassis equipped withpneumatic jacks conas structed in accordance with the invention.

Figure 2 is a longitudinal sectional view through one of the jacks takenon the line- 2-2 of Figure 1.

Figure 3 is across sectional view through the 40 distributor valve takenon the line H of Fig-- ure 1.

Figure 4 is across sectionalview the distributor valve taken on the line4-1 of Figure 1.

45 Referring now to the drawings in which likev characters of referencedesignate similar parts in the various views, ll designates the Irontaxle,

II the rear axle housing, l2 the chassis or frame,

is the motor, It the instrument board and ll 50 the wheels of .aconventional motor vehicle.

In carrying out the invention I provide a pneumatic jack for each, endof each axle comprising a cylinder 16 closed at the upper end andv openat the bottom, the cylinder having an axial-- 55 1y inlet e "in topermit a fluid pressure medium being supplied to the interior of thecylinder through an inlet pipe l8. The inlet passage I1 is connectedpressure tight to the pipe I! by means of conventional nut fittings l9and 20,

The lower end of the cylinder is threaded exteriorly to receive a screwcap 2| which is provided with an internal radially disposed shoulder 22that abuts the end 01' the cylinder and is further provided in theshoulder with an axially 10 eter oi the screw cap and at the endopposite the shoulder there is assembled with the screw capan annularinternally threaded nut 26 of approximately the same outer diameter asthe shoulder and of approximately the some inner I diameter as thethreaded bore of the screw cap. The nut 28 and shoulder 25 form stops orabut- 'ments to anchor-the cylinder against vertical movement relativelytothe securing clamp 21 25 which will be presently described in detail.

- A piston 28 is slidably fitted in the bore of the cylinder andprojects downwardly through ,an axial'opening 2! formed in the screwcap,

the lower end of the piston being equipped with a 30 caster wheel 3|having bearing balls 3| between the relatively rotatable members 32 and33 to take the thrust of the piston and permit the caster wheel toswivel when I the vehicle is being maneuvered as in shifting the motorvehicle from 35 place to place inside a garage, since-the piston itselfis non-rotatable due to the pressure required in the cylinder and uponthe piston to support the weight'oi a motor vehicle.

The piston is of novel construction, having the 40 upper end unii'ormlyreduced to provide a stem 34 upon which is slidably fitted a smooth borenut 35 forming a-piston head, the piston'being provided below the stemwith a uniformly enlarsed portion forming a collar 36 which slidablyfits the inner wall of thecylinder and below the collar the piston isprovided with. a uniformly enlarged portion iorming an annular boss 31which is of the same diameter as, and is adapted to seat in, the well 23when the piston is lowered and coact with the collar 36 in rigidlyreeniorcing'the piston to withstand lateral shocks and stresses when thepiston is in operative position. Anut "is threaded onto the end of thestemv 24 and confines the piston head 35 againsta fibrous washer 39which is interposed between the piston head 35 and the piston collar 36.Channels 40 are formed in the piston head 35 to permit access of thefluid pressure medium through the piston head and against the washer 39and collar 36. The lower end of the piston head is circumferentiallyrecessed and rounded to provide a recess 4| to receive the upturnedmarginal edge of the washer 39 so that the latter may most efiectivelyoperate to provide a pressure tight connection between the piston head,the piston collar, and the inner wall of'the cylinder.

A' helical spring 42, surrounds the piston 26 and boss or bearing 31,one end of the spring being seated against the lower face of the collar36 and the opposite end of the spring'being seated in the heretoforementioned seat 24 at the top of the well 23. When the piston is inoperative position with the piston head lowered to the dotted lineposition shown in Figure 2, the boss or bearing 31 will be snugly seatedin the well 23 while the spring 42 will be compressed between the collar36 andseat 24 to store up energy to return the-piston to its upper. orreleased position after each operation.

For securing the jack cylinder l6 to the axle or axle housing asthe'case may be the beforementioned securing clamp 21 comprises a bar 43which is provided with upper and lower arms 44 which are spaced apartsufiiciently to receive the axle or housing between them when thesecuring clamp is slipped laterally over the axle or axle housing, andthe arms are provided with elongatedslots 45 to receive the screwcap 2!,the, arms being rounded" at the ends, .as best shown in Figure 1, toprovide bearing surfaces for the annular nut 26 and collar 25 of thescrew cap. The screw cap is held against the rounded faces 46 of theslots by means of spacer blocks 41 disposed on opposite sides of theaxle [6 for example and confined between the bar 43 and the screw cap 2|by means of a set screw 48 threaded through the bar 43.

To assemble the parts the securing clamp is moved to straddle the axlewhereupon the cylinder IS with the nut 26-thereon may be inserteddownwardly through the upper slot in the securing clamp and the screwcap 2| may thereupon be screwed on to the cylinder until the shoulder 25abuts the lower arm 44 of the clamp. The set screw 48 may now betightened to draw the clamp. tight upon the axle and position the screwcap 2| against the rounded end walls 46 of the 'slots in thearms.

For supplying the pneumatic jacks with a fluid pressure medium,preferably gases formed by the explosions in the motor cylinders, adis-' tributor valvehousing 49 is preferably disposed on the rear faceof the instrument board 14 and as best shown in Figure 4 is providedwith a threaded cap or cover 50 having an axial tubular boss 5| whichprojects throughan opening 52 in the instrument board H. A nut 53 isthreaded 'cally opposite each other as best shown in Figure 3.

A valve 56 is rotatably mounted within the housing 49 and is providedwith a stem 51 which loosely fits in the boss 5| and is terminallyequipped with a knob 56 which is disposed within convenient reach of thedriver of the vehicle.

A dust plate 59 isdisposed on the stem 51- and 5 is bolted as shown. at66 or otherwise secured .to the instrument board. I

The valve 56 is provided with an axially disposed -distributor channel6| opening through the bottom face and in communication with a 10 pipe62 which terminates in two or more branches 63 that enter the combustionchambers of the motor cylinders for supplying the distributor channel ofthe valve with exploded gases under high pressure. The distributorchannel 6| is 15 provided with a radially disposed branch channel 64which opens through the cylindrical outer wall of the valve and may beturned selectively into registration with the inlet ports 54 to operateany desired jack. The branch channel 64 20 is provided with a ball checkvalve 65 which after the jack cylinder is filled and the piston forceddown to its limit of movement, will prevent release of pressure from thecylinder back through the distributor channel. 2

An arcuate pressure release channel 66 is disposed in the valve 56, thecenter of curvature of the channel being located on the outercylindrical wall of the valve, and the radius of curvature of thechannel being such that the channel 30 will cross connect one of thepipes l8 and the adjacent pressure release port 55 in the housing whenthe valve 56 is turned by the knob 58. The dust plate 59 it will beobserved by referring 35 to Figure 1 is provided with suitable indicia61 to indicate the position of the pipes l8 and pressure release port66.

By now referring to Figure 4 it will be seen that a tubular valve =68 isslidably fitted in the bore of the distributor channel 6| and is closedat the upper end and open at the bottom end to register with the pipe62. A rod 66 is integrally I connected with the closed upper end of thevalve and is slidably fitted in an opening 16 in the stem 51. A buttonII is fixed to the top of the rod outside of the knob 58 and forms meansfor raising and lowering the slide valve 68. The latter is provided witha lateral port 12 which registers with the'branch distributor channel 64when the valve is in lowered position but is moved out of registrationwith the branch channel so that the branch channel is sealed by thevalve when the valve is raised. A helical spring I3 is housed in thedistributor channel GI and is confined under tension between the endwall of the channel and the top of the slide valve to yieldably hold theslide valve at its downward limit of'movement. The pressure from theexploding gases being always in the pipe 62 will 50 force the slidevalve 66 upward to closed position to seal the distributor passage 64.When it is desired to operate any particular jack the passage 64 isbrought into registration with the pipe I 8 of that particular jackwhereupon the opera- 66 tor may press down on the button II to bring theport 12 of the slide valve into registration with the distributorchannel 64 and permit the pressure to equalize between the pipe 62 andthe' interior of the cylinder to force down the piston 70 to operativeposition.

Fromthe above description it is thought that the construction andoperation of my invention will be fully understood without furtherexplanation. I

being an What is claimed is:

11. The combination with the chassis of a mobottom of the cylinderhaving a seat for the spring at thetop thereof, the wall of the wellsnugly receiving said bearing boss when the piston isin operativeposition and reenforcing the piston to resist lateral stresses.

2. In a pneumatic jack for motor vehicles, a cylinder having an inlet atthe top adapted to admit a fluid pressure medium, a screw cap forming abottom for the cylinder and having a threaded inner wall engaging thecylinder, there axial opening in the bottom of the cap, a piston in thecylinder extending through said opening, a caster wheel on the bottom ofthe piston, said screw cap having an internal sho-ulider engaging theend of the cylinder, there being: an annular well disposed axially inthe shoulder and extending substantially halfway to the bottom exteriorface of the cap, a helical spring surrounding the piston, a shoulder onthe piston forming an abutment for one end of the sprinzg, said internalstandl lateral stresses.

shoulder on the screw cap Iormilng an abutment for the opposite end ofthe force the cylinder against the 3. In a pneumatic jack for motorvehicles, a cylinder having an inlet at the top to admit a fluidpressure medium, a piston in the cylinder, a. piston head having asmooth axial bore and having a recessed rounded bottom face, there beingpassages in the piston head opening through the top and the bottom facesof the piston head, auniformly reduced stem on the piston projectingthrough the bore of the pistonhead, a. nut threaded on said stem toretain the piston head on thepiston, a circumferential collar on a thepiston below and spaced from the piston head andengaging the wall of thecylinder, a

packing washer on the stem confined between the piston head and theshoulder and having the outer peripheral portion curved upwardly in saidrecess in the piston head and engaging the wall of the cylinder, saidpassages in the piston head conducting the fluid pressure medium fromabove the piston head to said curved marginal portion of the washer toforce the washer tightly against the wall of the cylinder to seal thepiston head pressure tight in the cylinder.

4. In a pneumatic jack for motor vehicles, the combination with a motorvehicle axle, of a cylinder, a screw cap forming a bottom -for thecylinder, spaced circumferential shoulders onthe cap forming steps. aU-shaped attaching clamp straddling the axle and having slots in thelegs receiving said screw cap, the stop shoulders of I the screw capbearing against the legs of the clamp and preventing verticaldisplacement of the cylinder on the clamp, spacer blocks embraced by theclamp-and disposed on opposite sides of the vehicle axle, and aset-screw carried by the clamp and engaging one of the blocks to endwalls of the slots in the clamp and rigidlysecure the cylinder to theaxle.

WALTER A. FEHRMANN.

